This invention relates generally to drilling, and more particularly, to drilling completely through an object underwater and capturing all process debris using high flow suction.
Nuclear reactor repairs and modifications often require machining operations such as drilling and milling within the reactor vessel and typically underwater. All machining debris should be retained in such machining operations and not allowed to infiltrate and contaminate the reactor. Known underwater drilling tool systems and methods address the basic requirement that the machining debris be retained.
One such method utilizes a high pressure direct water flow induced integral with the mechanics of the machining system to create a hydroplaning effect at the tool bit face. The high pressure water flow facilitates chip breakage from the surface and serves as the flowing medium to carry the chips to an integral chip containment receptacle. To completely assure that no debris escaped the cut, a secondary machining operation, such as electric discharge machining (EDM), is necessary to machine the final ligament on the back side of the cut. The method does not permit the tool bit to completely cut through the material. Rather, the EDM process, which does not produce machining debris, is used to complete the cut through the material. However, the EDM process is extremely slow.
It would be desirable to provide apparatus and methods to cut completely through an object underwater in a nuclear reactor and collect all machining debris without employing secondary machining operations, such as EDM.